1. Field of the Invention
The present invention relates generally to an apparatus and method for supporting different frame structures in a broadband wireless communication system, and more particularly, to an apparatus and method for communicating a control message including frame structure information in a broadband wireless communication system supporting different frame structures.
2. Description of the Related Art
Many wireless communication techniques are being proposed to achieve high-speed mobile communication. Among them, an Orthogonal Frequency Division Multiplexing (OFDM) scheme or an Orthogonal Frequency Multiple Access (OFDMA) scheme is accepted as one of the most promising techniques for a next generation wireless communication. The OFDM scheme is expected to be widely utilized in most of the wireless communication techniques in the future. In addition, the OFDM or OFDMA scheme is currently used as a standard in an Institute of Electrical and Electronics Engineers (IEEE) 802.16 based Wireless Metropolitan Area Network (WMAN) known as a 3.5 generation technology.
In order to facilitate flexible allocation of Uplink (UL)/Downlink (DL) resources in a Broadband Wireless Access (BWA) system based on the OFDM scheme, a Base Station (BS) transmits information regarding UL/DL resource allocation for each frame. For this purpose, a MAP message is used in the IEEE 802.16 based system.
FIG. 1 is a diagram illustrating a frame structure of a conventional IEEE 802.16 based system.
Referring to FIG. 1, a frame includes one DL frame and one UL frame. The DL frame is defined as a period in which a BS transmits data to a plurality of Mobile Stations (MSs). The UL frame is defined as a period in which the MSs transmit data to the BS.
The DL frame includes a preamble, a Frame Control Header (FCH), a DL-MAP, a UL-MAP, and a plurality of DL bursts. The UL frame includes a control region and a UL burst region. The DL preamble is used when an MS obtains initial synchronization and searches for a cell. The FCH contains information indicating a basic structure of the frame. The DL-MAP contains Information Elements (IEs) indicating a region of the DL bursts (e.g., location and size). The UL-MAP contains IEs indicating a UL frame structure.
The UL frame includes a ranging region and a plurality of UL bursts. The ranging region is defined as a region in which an MS can transmit a random access code. The ranging region is used to perform an initial network access, to request a handoff, to request resource allocation, etc.
In general, the frame structure is determined by the BS. For each frame, the MS receives the DL-MAP and UL-MAP transmitted from the BS, and thus recognizes the frame structure and resource allocation information.
In comparison with a legacy system, a communication system is being evolved to provide a high-speed data service or to solve implementation issues by modifying a standard or the like. In such a process, various systems may co-exit in the same area according to a compatibility with the legacy system. For example, in an area where an IEEE 802.16e system (i.e., legacy system) is installed, a new system, which is more evolved than the legacy system may be installed. In this case, the new system must be able to provide a service not only to a legacy MS but also to a new MS.
That is, the new system must support not only an old frame which includes an old MAP, burst, and control channel but also a new frame which includes a new MAP, burst, and control channel. In addition, the new MS must be able to distinguish an old frame structure and a new frame structure, and the legacy MS must be able to operate without errors upon receiving a new frame.